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Sender: Tejun Heo <htejun@gmail.com>
From:   Tejun Heo <tj@kernel.org>
To:     jiangshanlai@gmail.com
Cc:     torvalds@linux-foundation.org, peterz@infradead.org,
        linux-kernel@vger.kernel.org, kernel-team@meta.com,
        Tejun Heo <tj@kernel.org>
Subject: [PATCH 2/5] workqueue: Re-order struct worker fields
Date:   Tue, 18 Apr 2023 10:51:56 -1000
Message-Id: <20230418205159.724789-3-tj@kernel.org>
In-Reply-To: <20230418205159.724789-1-tj@kernel.org>
References: <20230418205159.724789-1-tj@kernel.org>
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struct worker was laid out with the intent that all fields that are modified
for each work item execution are in the first cacheline. However, this
hasn't been true for a while with the addition of ->last_func. Let's just
collect hot fields together at the top.

Move ->sleeping in the hole after ->current_color and move ->lst_func right
below. While at it, drop the cacheline comment which isn't useful anymore.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
---
 kernel/workqueue_internal.h | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/kernel/workqueue_internal.h b/kernel/workqueue_internal.h
index b3b4b2b41d93..902459b328de 100644
--- a/kernel/workqueue_internal.h
+++ b/kernel/workqueue_internal.h
@@ -32,9 +32,12 @@ struct worker {
 	work_func_t		current_func;	/* L: current_work's fn */
 	struct pool_workqueue	*current_pwq;	/* L: current_work's pwq */
 	unsigned int		current_color;	/* L: current_work's color */
-	struct list_head	scheduled;	/* L: scheduled works */
+	int			sleeping;	/* None */
+
+	/* used by the scheduler to determine a worker's last known identity */
+	work_func_t		last_func;	/* L: last work's fn */
 
-	/* 64 bytes boundary on 64bit, 32 on 32bit */
+	struct list_head	scheduled;	/* L: scheduled works */
 
 	struct task_struct	*task;		/* I: worker task */
 	struct worker_pool	*pool;		/* A: the associated pool */
@@ -45,7 +48,6 @@ struct worker {
 	unsigned long		last_active;	/* L: last active timestamp */
 	unsigned int		flags;		/* X: flags */
 	int			id;		/* I: worker id */
-	int			sleeping;	/* None */
 
 	/*
 	 * Opaque string set with work_set_desc().  Printed out with task
@@ -55,9 +57,6 @@ struct worker {
 
 	/* used only by rescuers to point to the target workqueue */
 	struct workqueue_struct	*rescue_wq;	/* I: the workqueue to rescue */
-
-	/* used by the scheduler to determine a worker's last known identity */
-	work_func_t		last_func;
 };
 
 /**
-- 
2.40.0